where is viewport unlink feature in blender 2.8
In my case I had two characters on different layers in Blender 2.79 and I used unlink viewport to see them both on the screen at the same time.

In Blender 2.82 there is no unlink viewport button, but since I had the characters in separate layers they were imported in as separate collections.

If you go to you workspace and select the View tab on the right side, then select collections at the bottom, you can then use local collection. Then you can hide the other collections you are not using. This will allow you to manipulate each character in their own workspace.